Here's the Markdown shortcut you can use on new empty lines: $.
To add an inline formula, use $formula$ .
Inside the LaTeX block, you may use any standard notation for a math environment, and you should not wrap your content with $ since the math context is already set.
Editing
To edit a LaTeX block, click it once. Alternatively, you can navigate to it using the arrows on your keyboard.
To exit the editing mode, click away from the block. Alternatively, you can also use the arrow keys.
Examples
Here's how LaTeX equations would look like in the editor:
E=mc^2
E=mc2
Resources
To learn how to write equations in LaTeX, the following resources are available on the Internet: